Atoms are greedy

Yes they are.

Atoms have the same number of protons as their electrons, therefore they're neutral. However, atoms have a level of electronegativity and ionization energy. Electronegativity describes how greedy atoms of a given element are, or their tendencies to attract electrons. The trend of electronegativity increases from the bottom left to the top right of the table. The least electronegative atom is Cesium because it has the most electron shells, which makes it hold its electrons very loosely. Opposite Cesium is Flourine, with the highest level of electronegativity because it holds its many electrons very tightly. The noble gases generally do not have any electronegativity because their electron shells are full.

Ionization energy is the amount of energy it takes to remove an electron from an atom's outermost valence shell. Similar to the electronegativity trend, the amount of energy increases from the bottom left to the top right. Helium has the highest ionization energy because it holds its electrons very tightly and has its electron closest to the positive nucleus (because it only has one shell), and therefore it requires the most energy to pull the electron off.